This invention relates broadly to flexible bearings, and more specifically to bearings that are constructed of alternate layers of reinforced elastomer and rigid shims, stacked and bonded together; so that they are flexible in directions parallel to the layers, but are relatively unyielding in directions perpendicular thereto. The invention described herein was made during the course of or under Contract Number N 0003072C0108 with the U.S. Navy.
This type of bearing has many uses, including applications to motor mounts and bridge abutments. More recently, it has been found to be useful for mounting a movable thrust nozzle to a rocket, so that the nozzle may be rotated from side to side for steering the rocket. A typical arrangement of the bearing for this use is shown in FIG. 3 of U.S. Pat. No. 3,429,622 to R. E. Lee, et al., wherein the bearing is labeled "10."
Other U.S. Patents showing this type of flexible bearing are U.S. Pat. Nos. 3,390,899, to J. T. Herbert, et al.; 3,504,902 and 3,504,903 to A. S. Irwin; and 3,504,904 to A. S. Irwin, et al.
When applied to thrust nozzles for rockets, flexible bearings of this construction are commonly quite thick in order to contain enough elastomer to permit a useful degree of angular displacement of the thrust nozzle. Because of the tendency of thick layers of elastomer to be extruded from between the rigid shims, elastomer is conventionally divided into a large number of thin layers -- requiring the use of a large number of rigid shims.
In order to promote precision control of the rocket, it is desirable that the thrust nozzle be rotatable about a fixed point. Hence, the rigid shims must all conform to surfaces of concentric spheres to accomplish this objective. Since each shim, therefore, conforms to a sphere of a different radius from all other shims, manufacture of such a bearing is a laborious and expensive process.